Array.prototype._filter = function (Fn) {
  const res = [];
  const arr = this;
  const len = arr.length;
  for (let i = 0; i < len; i++) {
    const callback = Fn.call(arr, arr[i], i, arr, arr);
    if (callback) res.push(arr[i]);
  }
  return res;
};
console.log([1, 2]._filter((i) => i > 1));

// [1, 2].filter((val, idx, array), context);
